Eighteen months into his pontificate, Pope Leo XIII, formerly Joachim Pecci, cardinal and bishop of Perugia, published the encyclical Aeterni Patris (“Of the Eternal Father”). The aim of the encyclical was to aid and advance the restoration of Christian philosophy, which had fallen into danger and disrepute by adhering to modern trends in secular philosophy, by urging a return to the scholastic thinkers of the Middle Ages, most especially the “Angelic Doctor” St. Thomas Aquinas. The encyclical attempts to clarify the roles of faith and philosophy, showing how most beneficially each may profit from the other. And according to the encyclical, the philosophy most conformable and useful for the faith is that of St. Thomas. The vigorous reintroduction of St. Thomas into the Catholic philosophic